Powered systems, such as vehicles, can be powered by consumption of hydrocarbon-based fuels. Some vehicles may consume natural gas to generate tractive effort and other electric power for propelling the vehicles. The propulsion systems of such vehicles may operate more efficiently (e.g., generate or produce more work per unit of fuel) when the natural gas supply to the propulsion systems includes or is formed from methane as opposed to other heavier hydrocarbons, such as ethane, butane, etc. Because the supply of natural gas to the propulsion systems may include impurities such as these heavier hydrocarbons, the vehicles may operate less efficiently at times. A need exists for a sensor that can detect the presence of one or more of these heavier hydrocarbons.
Conventional gas sensors for hydrocarbons, however, are non-selective devices exhibiting significant gas cross sensitivity and thus, low gas selectivity. For example, these sensors may not be able to differentiate between the desirable methane and less desirable, heavier hydrocarbons. The origin of this limitation of conventional sensors of being non-selective is in the conflicting requirements for sensor selectivity and sensor reversibility. The full and fast reversibility of sensor response is achieved via weak interactions between the analyte and a sensing film of the sensor, whereas the high selectivity of sensor response is achieved via strong interactions between the analyte gas and the sensing film.